U.S. patent application 61/014,031 to the inventor is incorporated hereby by reference in its entirety.
An aneurysm is a localized, blood-filled dilation (bulge) of a blood vessel caused by disease or weakening of the vessel wall. Left untreated, the aneurysm will frequently rupture, resulting in loss of blood through the rupture and death.
Aneurysms may involve arteries or veins and have various causes. They are commonly further classified by shape, structure and location. Aortic aneurysms are the most common form of arterial aneurysm and are life threatening. The aorta is the main artery which supplies blood to the circulatory system. The aorta arises from the left ventricle of the heart, passes upward and bends over behind the heart, and passes down through the thorax and abdomen. Among other arterial vessels branching off the aorta along its path, the abdominal aorta supplies two side vessels to the kidneys, the renal arteries. Below the level of the renal arteries, the abdominal aorta continues to about the level of the fourth lumbar vertebrae (or the navel), where it divides into the iliac arteries. The iliac arteries, in turn, supply blood to the lower extremities and perineal region.
It is common for an aortic aneurysm to occur in that portion of the abdominal aorta between the renal arteries and the iliac arteries. This portion of the abdominal aorta is particularly susceptible to weakening, resulting in an aortic aneurysm. Such an aneurysm is often located near the iliac arteries. An aortic aneurysm larger than about 5 cm in diameter in this section of the aorta is ominous. Left untreated, the aneurysm may rupture, resulting in rapid, and usually fatal, hemorrhaging. Typically, a surgical procedure is not performed on aneurysms smaller than 5 cm because no statistically demonstrated benefit exists in performing such procedures.
Aneurysms in the abdominal aorta are associated with a particularly high mortality rate; accordingly, current medical standards call for urgent operative repair when aneurysm diameter is larger than 5 cm. Abdominal surgery, however, results in substantial stress to the body. Although the mortality rate for an aortic aneurysm is extremely high, there is also considerable mortality and morbidity associated with open surgical intervention to repair an aortic aneurysm. Repair of an aortic aneurysm by surgical means is a major operative procedure. Substantial morbidity accompanies the procedure, resulting in a protracted recovery period. Further, the procedure entails a substantial risk of morbidity and mortality, mostly due to the cardiopulmonary bypass employed in such a procedure.
Therefore, less invasive methods have been introduced to attempt to treat an aortic aneurysm without the attendant risks of intra-abdominal surgery. Among them are inventions such as U.S. Pat. No. 4,562,596 which discloses an aortic graft constructed for intraluminal insertion; U.S. Pat. No. 4,787,899 teaches an intraluminal grafting system includes a hollow graft which has a plurality of staples adapted proximate its proximal end. The system includes a guide for positioning the proximal end of the graft upstream in a lumen which may be a blood vessel or artery; and U.S. Pat. No. 5,042,707 which presents a stapler, adapted to be inserted into a blood vessel and moved to a desired position therealong, and having a selectively-articulatable distal marginal end portion used to staple a graft to the interior wall of the blood vessel.
Hence, although in recent years certain techniques have been developed that may reduce the stress, morbidity, and risk of mortality associated with surgical intervention to repair aortic aneurysms, none of the systems that have been developed effectively treat the aneurysm and exclude the affected section of aorta from the pressures and stresses associated with circulation. None of the devices disclosed in the references provide a reliable and quick means to reinforce an aneurysmal artery. In addition, all of the prior references require a sufficiently large section of healthy aorta surrounding the aneurysm to ensure attachment of the graft. The neck of the aorta at the cephalad end (i.e., above the aneurysm) is usually sufficient to maintain a graft's attachment means. However, when an aneurysm is located near the iliac arteries, there may be an ill-defined neck or no neck below the aneurysm. Such an ill-defined neck would have an insufficient amount of healthy aortic tissue to which to successfully mount a graft. Furthermore, much of the abdominal aorta wall may be calcified which may make it extremely difficult to attach the graft to the wall.
Shortcomings of the presently available endovascular stent-graft products include endoleaks, anatomic variability, anatomic non-conformity, migration/dislocation, discontinuities of endoluminal profile and thrombogenicity.
Endoleaks are caused by passage of blood into the aneurismal space subsequent to stent-graft placement. Research has exposed yet another problem which indicates that the necks of the post-surgical aorta increase in size for approximately twelve months, regardless of whether the aneurysm experiences dimensional change. This phenomenon can result in perigraft leaks and graft migration. Anatomic variability: although sizing of “tube” or “bifurcated” grafts is radiographically assessed prior to surgery, it is necessary for the surgeon to have a large selection of graft lengths and diameters on hand to ensure an appropriate surgical outcome. Anatomic non-conformity: placement of a circularly-profiled graft with an associated fixation device within an essentially “ovoid”-profiled vessel. Migration/dislocation also caused due to the use of attachment means which fasten only to the insubstantial, structurally compromised (diseased) intima and media levels of the vessel wall. Discontinuities of endoluminal profile are potential contributors to hemodynamic disturbances that might lead to non laminar, or even turbulent flow regimen. This in turn can contribute to increased clot formation. Thrombogenicity: manufactured of synthetic polymers, contemporary vascular liners present a luminal surface that is typically far more thrombogenic than the native arterial intimal tissue such devices cover.
Unfavorable anatomy relating to the neck of the aneurysm is the most common reason for patients being rejected for EVAR. Short or absent infrarenal neck, large aortic diameters, and excessive angulation at this level are the main problems.
Furthermore, progressive expansion of the aneurysm sac associated with type I endoleak can lead to compromise of seal at the neck and is the principal indication for secondary intervention for this condition.
Means and method for repairing aortic aneurysms, especially an implementable kit and methods thereof useful for treating an aneurysmatic abdominal aorta, avoiding the dislocation of the implanted kit along the aorta, are still a long felt need.